1,511,305 research outputs found
Mixed symmetric baryon multiplets in large QCD: two and three flavours
We propose a new method to study mixed symmetric multiplets of baryons in the
context of the expansion approach. The simplicity of the method allows
to better understand the role of various operators acting on spin and flavour
degrees of freedom. The method is tested on two and three flavours. It is shown
that the spin and flavour operators proportional to the quadratic invariants of
SU(2) and SU(3) respectively are dominant in the mass formula.Comment: 7 pages, 2 tables, talk given by Fl. Stancu at Mini-Workshop
"Dressing Hadrons", Bled, Slovenia, July 4-11, 201
Method for Extracting the Glueball Wave Function
We describe a nonperturbative method for calculating the QCD vacuum and
glueball wave functions, based on an eigenvalue equation approach to
Hamiltonian lattice gauge theory. Therefore, one can obtain more physical
information than the conventional simulation methods. For simplicity, we take
the 2+1 dimensional U(1) model as an example. The generalization of this method
to 3+1 dimensional QCD is straightforward.Comment: 3 pages, Latex. Presented at Lattice 97: 15th International Symposium
on Lattice Field Theory, Edinburgh, Scotland, 22-26 Jul 1997, to appear in
Nucl. Phys. B(Proc. Suppl.
A Constructive Characterisation of Circuits in the Simple (2,2)-sparsity Matroid
We provide a constructive characterisation of circuits in the simple
(2,2)-sparsity matroid. A circuit is a simple graph G=(V,E) with |E|=2|V|-1 and
the number of edges induced by any is at most 2|X|-2.
Insisting on simplicity results in the Henneberg operation being enough only
when the graph is sufficiently connected. Thus we introduce 3 different join
operations to complete the characterisation. Extensions are discussed to when
the sparsity matroid is connected and this is applied to the theory of
frameworks on surfaces to provide a conjectured characterisation of when
frameworks on an infinite circular cylinder are generically globally rigid.Comment: 22 pages, 6 figures. Changes to presentatio
Convergent Calculation of the Asymptotic Dimension of Diffusion Limited Aggregates: Scaling and Renormalization of Small Clusters
Diffusion Limited Aggregation (DLA) is a model of fractal growth that had
attained a paradigmatic status due to its simplicity and its underlying role
for a variety of pattern forming processes. We present a convergent calculation
of the fractal dimension D of DLA based on a renormalization scheme for the
first Laurent coefficient of the conformal map from the unit circle to the
expanding boundary of the fractal cluster. The theory is applicable from very
small (2-3 particles) to asymptotically large (n \to \infty) clusters. The
computed dimension is D=1.713\pm 0.003
Improved High Contrast Imaging with On-Axis Telescopes using a Multi-Stage Vortex Coronagraph
The vortex coronagraph is one of the most promising coronagraphs for high
contrast imaging because of its simplicity, small inner working angle, high
throughput, and clear off-axis discovery space. However, as with most
coronagraphs, centrally-obscured on-axis telescopes degrade contrast. Based on
the remarkable ability of vortex coronagraphs to move light between the
interior and exterior of pupils, we propose a method, based on multiple
vortices, that, without sacrificing throughput, reduces the residual light
leakage to (a/A)^n, with n >=4, and a and A being the radii of the central
obscuration and primary mirror, respectively. This method thus enables high
contrasts to be reached even with an on-axis telescope.Comment: 3 pages, 2 figure
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